Today it is very common that quick couplers are used for connecting different tools to an earth moving machine, for example an excavator, backhoe loader or a digger. With the quick coupler the driver can quickly and simply switch between different tools, for example different buckets, which can be used for s certain work condition. The quick coupling is mounted directly on the excavator art or on a on the arm mounted tilt rotator which allow tool movement in all directions. It can also be integrated in the tilt rotator. The quick coupling has in its lower part a locking mechanism adapted to lock the tool, either mechanically or with a hydraulically controlled lock. The locking mechanism often comprises a solid grip and a locking wedge or locking pins which locks the tool around parallel axles attached to the attachment bracket.
Quick couplers can be divided into two groups; universal or dedicated. Universal quick couplers are characterized in that the quick coupler is constructed to be able to be used on tools originating from different tool manufactures. Since the tools originate from different tool manufacturers or different excavator models, the distance between the parallel axles can vary and the diameter of the axles can be different. Thus, a universal quick coupler normally fits tools with different distances between the axles and sometimes also fit tools with different axle diameter. Dedicated quick couplers are, on the other hand, based on a standard, which result in that the quick coupler only fits if the tool follows the standard from which the quick coupler is constructed. Only the upper part, i.e. the part mounted adjacent the excavator arm, varies while the locking mechanism follows a standard. The most common standard for quick couplers on the Nordic market is symmetrical quick couplers, which are based on a gate with two parallel axles.
A problem with quick couplers of today is that the lock indication often is indistinct and not always secure. Today normally an indicator rod/indicator pin is used which is connected to the locking arrangement of the quick coupler. This means that when the locking arrangement is retracted into the holder the lock is opened and the indicator rod becomes visible, which indicates that the lock is open. Such solutions are for example disclosed in WO02097201A1 , U.S. Pat. No. 6,379,075B1 and U.S. Pat. No. 6,132,130A. Thus, the normal is that the quick coupler has a negative lock indication, i.e. it indicates when the lock is open. The risk with this solution is, if the indicator rod in either way is broken or removed the driver may believe that the lock is closed, since no indicator rod is visible, while it actually is open. In such case the risk is large that the tool is dropped, which can be dangerous for personnel working in the vicinity of the excavator.
Other locking arrangements are also know which makes it possible to indicate when the lock is locked. Such quick coupler lock indication arrangements are for example shown in US20100189535A1, EP0527733B1 and U.S. Pat. No. 5,692,855A.
In both US20100189535A1 and EP0527733B1 a locking arrangement is disclosed having the shape of a, in relation to the quick coupler, laterally extending hydraulically actuated pin, which both see to that the lock remains locked and which, with a colored outer part visible for the driver, indicates that this is the case. U.S. Pat. No. 5,692,855A shows a coupling arrangement where a handle visible for the observer is turned together with the locking arrangement and indicates locked and unlocked position, respectively.
These solutions either demand an extra hydraulic actuator and/or several mechanically connected components which can be loose or break. Thus, there is a need for a simple and reliable lock indicator for a quick coupler which clearly indicated for that driver that the tool is securely locked to the excavator.